This invention relates to an electrically heated soldering iron, in which the heat is generated in the soldering tip by electrical resistance.
Soldering is a well known method of joining two or more metals together using a metallic solder having a low eutectic temperature. The solder is heated until it is liquefied, and the metals to be joined are also heated. The solder is introduced into the interface between the metals where it cools and solidifies to securely bond the metals through the interface.
One method of soldering involves melting a quantity of solder using an open flame, such as a blow torch. The flame also heats the end or xe2x80x98bitxe2x80x99 of the soldering iron which is then used to apply heat to the interface as solder is poured into the interface. The bit can be in the shape of a pencil point or rounded point, or a blade, depending on the specific application. Although this technique has been in use for many years, the use of in open flame around combustible materials can create a potential fire hazard, thereby limiting its usefulness.
In addition to the use of an open flame to melt the solder, and to heat the soldering tip and substrate, there are other ways of achieving the same objective. One such approach is to use an electric current to heat the soldering iron by resistance heating. Various types of soldering tips can be used. For example, a split tip can be applied to a metallic substrate to complete an electric circuit causing the tip and the surrounding surface to reach operating temperature quickly. Concurrently, the low melting temperature solder is introduced to the heated surface of the substrate where the solder melts, flows, and subsequently is allowed to cool.
Using an electrical transformer, a low voltage-high amperage electrical current is passed through copper wire, steel conductors (buss bars), and graphite electrodes into a metal soldering tip. Electrical resistance in the solder tip produces heat that is transmitted to the bit and then to the surface of the materials to be soldered. The soldering tip can be pivoted with respect to the handle, enabling the user to solder at multiple angles to the work piece.
The present invention relates to a soldering iron. The iron comprises a soldering tip and a pair of conductors in electrical contact with the soldering tip, the conductors preferably comprising a form of carbon adapted to be connected to a source of electrical current that passes through the conductors to generate heat within the soldering tip. Each carbon conductor is an electrode that may be secured to a buss bar utilizing a fastener. The electrodes may have a trapezoidal cross-sectional shape that engages a corresponding slot in the soldering tip. Alternatively, they may have a surface that conforms to and frictionally engages the axial surface of the soldering tip. The soldering iron includes a suitable handle which enables the user to safely and comfortably use the soldering iron without the risk of being burned. The soldering iron may further be provided with a pivot structure to permit the user to adjust the angle of the soldering tip with respect to the handle.
The invention further relates to a method of using an electrical soldering iron to solder contiguous metal pieces together, or, for example, to seal a leak in a metal pipe or conduit. The soldering iron comprises a soldering tip, having a longitudinally extending body joined to a source of electrical current. A handle permits the user to manipulate the soldering iron to solder according to the invention. The method comprises the following steps:
When joining metal pieces together, the pieces to be joined by solder are juxtaposed next to one another. These pieces typically may comprise pieces of sheet metal of the type that is used for roofing or for gutters. The body of the soldering tip is secured between a pair of shaped carbon electrodes and an electrical current is passed through the electrodes to heat the tip to soldering temperature. The solder is flowed onto the juxtaposed pieces. The solder is allowed to cool to join the pieces together. In one embodiment, the step of securing the body between the electrodes includes the added steps of providing two diametrically opposed, blind, longitudinal slots in the body, and inserting the carbon electrodes into the slots. The electrodes may be secured to the body using an insulated washer, such as a ceramic disc screwed into the flat end of the body. Means may also be included to permit the soldering tip and electrodes to be pivoted with respect to the handle. When being used to repair a leak, the soldering iron is used to heat the metal surface around the leak and to heat the solder, causing it to flow into the hole causing the leak. When the iron is withdrawn, the solder solidifies to seal the hole.
In another embodiment, the electrodes are shaped by machining or molding or other suitable means to conform them to the body perimeter of the soldering tip. Then the electrodes are clamped to the body. This permits the electrodes to be unclamped to allow longitudinal adjustment of the soldering tip with respect to the electrodes.
In yet another embodiment, the two electrodes are cylindrical plugs that are inserted into corresponding holes on opposite sides of the body of the soldering tip. The electrodes are bolted or otherwise joined to the buss bars so that the electrodes and the soldering tip can be rotated with respect to the buss bars by loosening the bolts or other fasteners for rotation and then tightening the same to fix the angle of rotation. The electrodes may be externally threaded and screwed into the body. Alternatively, they may be cemented in place or press fit into the corresponding holes.
The invention further covers a device for the resistance soldering of heavy pieces, such as sheet metal. The device includes a source of low voltage electrical current, such as a step-down transformer. It furthermore comprises a soldering iron with a soldering tip having a longitudinally extending body terminating in a point. The body is round, oval or polygonal in cross-section. The iron also has a pair of graphite electrodes joined to the source of low voltage electrical current and electrically coupled to the body of the soldering tip. A handle is provided with which to safely hold the soldering iron during use. The body of the soldering tip includes two blind, longitudinally extending slots positioned peripherally on opposite sides of the body. The graphite electrodes are conformally shaped to fit into the slots and are held in place by an insulated washer secured to the body of the soldering tip. The washer preferably is a ceramic disc secured to the body with a bolt or other fastener threaded into a hole tapped into a flat end of the soldering tip opposite the bit. The electrodes and the body of the soldering tip may be made to be pivotally movable with respect to the handle. This is achieved by using a pair of buss bars threadedly joined to the electrodes with threaded connectors whereby the connectors may be loosened to permit relative rotation between the handle and the electrodes. Instead of the graphite electrodes fitting into slots in the body of the soldering tip, the electrodes may be shaped to conform to the periphery of the body. A suitable clamping device is used to secure the body between the electrodes and to either permit or to limit relative movement of the body with respect to the electrodes. By loosening the clamping means, the body may be slid longitudinally between the electrodes to either extend or to shorten the overall length of the soldering iron. As another alternative, the two electrodes are shaped as cylindrical plugs that fit into corresponding holes on opposite sides of the soldering tip. The electrodes are bolted or otherwise joined to the buss bars so that the electrodes and the soldering tip can be rotated with respect to the buss bars by loosening the bolts or other fasteners and then tightening the same to fix the angle of rotation.